Local Structure and Hyperfine Interactions of 57Fe in NaFeAs Studied by Mossbauer Spectroscopy

Abstract

Detailed 57Fe Mossbauer spectroscopy measurements on superconducting NaFeAs powder samples have been performed in the temperature range 13 K < T < 300 K. The 57Fe spectra recorded in the paramagnetic range (T > TN ~ 46 K) were discussed supposing that most of the Fe2+ ions are located in distorted (FeAs4) tetrahedral of NaFeAs phase, while additional minor (< 10%) component of the spectra corresponds to impurity or intergrowth NaFe2As2 phase with a nominal composition near "NaFe2As2". Our results reveal that the structural transition (TS ~ 55K) has a weak effect on the electronic structure of iron ions, while at T < TN the spectra show a continuous distribution of hyperfine fields HFe . Shape of these spectra was analyzed in term of two models: (i) an incommensurate spin density wave modulation of iron magnetic structure, (ii) a formation of a microdomain structure or phase separation. It was shown that the hyperfine parameters obtained using these two methods have very similar values over the whole temperature range. The analysis of the temperature dependence HFe(T) with the Bean-Rodbell model leads to ksi = 1.16 +/- 0.05, suggesting that the magnetic phase transition is first-order in nature. A sharp evolution of the VZZ(T) and etha(T) parameters of the full Hamiltonian of hyperfine interactions near T ~ (TN, TS), were interpreted as a manifestation of the anisotropic electron redistribution between the dxz, dyz- and dxy-orbitals of the iron ions.

This paper has been withdrawn by the author due to conflict of interests

References in corpus (19)

• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• Theory of Electron Nematic Order in LaOFeAs
• Spin-orbital frustrations and anomalous metallic state in iron-pnictide superconductors
• Phase transitions in LaFeAsO: structural, magnetic, elastic, and transport properties, heat capacity and Mossbauer spectra
• Magnetism in Fe-based superconductors
• Commensurate Spin Density Wave in LaOFeAs: A Local Probe Study
• Structural and magnetic phase transitions in the ternary iron arsenides SrFe2As2 and EuFe2As2
• Structure, antiferromagnetism and superconductivity of the layered iron arsenide NaFeAs
• Puzzle of the gamma-alpha and other phase transitions in cerium
• Influence of the rare-earth element on the effects of the structural and magnetic phase transitions in CeFeAsO, PrFeAsO, and NdFeAsO
• Spin Ordering in LaOFeAs and Its Suppression in Superconductor LaO0.89F0.11FeAs Probed by Mössbauer Spectroscopy
• Competition of magnetism and superconductivity in underdoped (Ba1-xKx)Fe2As2
• Coexistence and competition of magnetism and superconductivity on the nanometer scale in underdoped BaFe1.89Co0.11As2
• Shape of spin density wave versus temperature in AFe2As2 (A=Ca, Ba, Eu): A Mössbauer study
• Incommensurate spin density wave in Co-doped BaFe2As2
• Crossover from commensurate to incommensurate antiferromagnetism in stoichiometric NaFeAs revealed by single-crystal 23Na,75As-NMR experiments
• Anisotropic resistivity of Na${}_{1-\delta }$Fe${}_{1-x}$Co${}_x$As
• Commensurate antiferromagnetic ordering in Ba(Fe{1-x}Co{x})2As2 determined by x-ray resonant magnetic scattering at the Fe K-edge
• Homogeneous coexistence of SDW and SC states in CaFe(1-x)Co(x)AsF studied by nuclear magnetic resonance

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